Multi-station deposition apparatus and method

ABSTRACT

A multi-station deposition apparatus capable of simultaneous processing multiple substrates using a plurality of stations, where a gas curtain separates the stations. The apparatus further comprises a multi-station platen that supports a plurality of wafers and rotates the wafers into specific deposition positions at which deposition gases are supplied to the wafers. The deposition gases may be supplied to the wafer through single zone or multi-zone gas dispensing nozzles.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of co-pending U.S. patent applicationSer. No. 10/124,309, filed Apr. 16, 2002, which is herein incorporatedby reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to chemical vapor deposition processes.More particularly, the invention relates to a multi-station depositionapparatus and method.

2. Description of the Background Art

As the size of integrated circuit (IC) devices decreases, the depositiontechniques used to form very thin films on substrates has become thefocus of much interest. To deposit thin films into ultra-high aspectratio vias and trenches (e.g., aspect ratios on the order of 20:1),atomic layer deposition (ALD) has been used.

An ALD technique deposits a thin film having a thickness of less than 50Å by alternating the supply of reactant gases and purging gases. Eachreactant gas is adsorbed onto the wafer as a monolayer, i.e., a layerbeing substantially one atom thick. The monolayers of various reactantgas react with one another to form a thin film. A thin film having ahigh aspect ratio, good uniformity, as well as good electrical andphysical properties can be formed using an ALD process. Also, the ALDfilms have a lower impurity density than those formed by otherdeposition methods.

ALD generally involves positioning a wafer in a chamber, generating avacuum in the chamber, and applying certain reactant gases in shortbursts (or pulses) to form a thin film upon the substrate. A purge gasmay be applied in between reactant gas bursts. Each burst results in theadsorption of a monolayer of gas. The application of gas bursts may berepeated to deposit a thicker film. Once a film of desired thickness isformed, a purge gas is used to remove residual reactant gases from thechamber, the chamber vacuum is released, and the wafer is removed fromthe chamber.

In one particular example of ALD, a thin tungsten layer may be formed byalternately pulsing silane (SiH₄) gas and tungsten hexafluoride (WF₆)gas into a chamber. The reaction between the adsorbed gases on thesurface of the wafer produces a thin tungsten film. After the thin layeris formed, hydrogen-reduced tungsten hexafluoride can be used to “bulkfill” tungsten onto the nucleation layer. Such an ALD-based processresults in very good step coverage of ultra-high aspect ratio trenchesand vias.

One method believed to overcome the inherent slowness of an ALD processis a batch process that simultaneously processes many wafers. Some batchprocesses involve stacks of processing zones having multiple wafersplaced in the zones. Within each zone, a laminar flow of reactant gasesis supplied over each wafer in the stack. Although effective atsimultaneously processing multiple wafers, the stacked zone processingtechnique has limited throughput.

Therefore, there is a need in the art for a method and apparatus for ALDprocessing of multiple wafers simultaneously such that wafer throughputis improved.

SUMMARY OF THE INVENTION

The present invention is a method and apparatus for performing atomiclayer deposition (ALD) processes or chemical vapor deposition (CVD)processes upon multiple wafers simultaneously.

In one embodiment, the multi-wafer deposition apparatus comprises aseries of deposition stations that are positioned upon a rotatingplaten. Above each station on the rotatable platen is at least one gasdelivery nozzle or showerhead that dispense reactant gases. The nozzlesat each station supply gases that perform the various stages of thedeposition process to form a particular film or film combination upon awafer. Each station is separated from other stations by a gas curtain.The gas curtains produce a barrier to inhibit reactant gases used in onestation from passing to an adjacent station.

In operation, a wafer is positioned on a wafer support in a firststation using a wafer transfer robot. A gas nozzle (or showerhead)dispenses a first reactant gas into a region above the wafer such thatthe first reactant gas is adsorbed upon the wafer. A burst of the firstreactant gas may be followed by a burst of purge gas. Alternatively, thepurge gas may be continuously supplied to the nozzle and a burst ofreactant gas may be inserted into the purge gas flow. The purge gasremoves any residual reactant gas that was not adsorbed onto the wafer.The first reactant gas is constrained to the first station by gascurtains formed on either side of the wafer support. The curtains formradials from a center hub of the rotatable platen to the edge of theplaten. An inert purge gas is used to form the curtains.

Next, the platen is rotated to position the wafer in the first stationbeneath a second nozzle that supplies another reactant gas. A pulse ofthe second reactant gas is applied to the wafer and the second reactantgas reacts with the first reactant gas to form a layer of material. Sucha deposition process forms a thin layer (sometimes referred to as amonolayer) in an atomic layer deposition (ALD) mode.

While the first station is receiving the second gas at the second platenposition, a second wafer can be placed in a second station on the platenand have the first reactant gas applied thereto. At each platenposition, the wafer temperature can be adjusted to optimize the reactionand/or adsorption that is to occur at that position. The same reactantgases may be applied from additional nozzles such that the film can beincreased in thickness. Alternatively, the wafers can be repeatedlyreturned to the first two nozzles to increase the film thickness,leaving other nozzles for other gases, e.g., bulk fill gases.

In another alternative embodiment, each station may be used to depositmultiple gases either sequentially or simultaneously such that theapparatus deposits material in a chemical vapor deposition mode. If thegases are supplied sequentially, a purge gas may be supplied to thewafer in between each of the applications of reactant gas. To facilitatedispensing one or more gases in a station, a multi-zone nozzle is used.A multi-zone nozzle comprises a plurality of conduits that each coupleto a plenum and each plenum provides gas to a disbursement port.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a perspective view of an embodiment of a deposition apparatusaccording to the present invention;

FIG. 2 is a top plan view of a rotatable platen used in the apparatus ofFIG. 1;

FIG. 3 is a plan view of a gas distribution manifold;

FIG. 4 is a cross-sectional view of the gas distribution manifold ofFIG. 3 taken a long line 4-4;

FIG. 5 is a cross-sectional view of a showerhead;

FIG. 6 is a schematic view of one station of the apparatus of FIG. 1;

FIG. 7 depicts a flow diagram of the operation of one embodiment of thepresent invention;

FIG. 8 is a perspective view of a second embodiment of an atomic layerdeposition apparatus according to the present invention;

FIG. 9 is a cross sectional view of another embodiment of anozzle—specifically a multi-zone nozzle;

FIG. 10 is a plan view of one embodiment for the multi-zone nozzle ofFIG. 9;

FIG. 11 is a plan view of an alternative embodiment of the multi-zonenozzle of FIG. 9;

FIG. 12 is a block diagram of a gas delivery system for a multi-zonenozzle of FIG. 9; and

FIG. 13 is a flow diagram of the operation of an embodiment of theinvention that dispenses gas in a chamber using a multi-zone nozzle.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an embodiment of a deposition apparatus100 according to the present invention. While FIG. 1 provides anillustration of the entire embodiment, FIG. 2 depicts a top plan view ofa rotatable platen 102 so as to clearly depict the plurality ofdeposition stations, 202A-202F within the apparatus 100. To bestunderstand the invention, FIGS. 1 and 2 should be viewed simultaneously.The apparatus 100 comprises a chamber 150, a gas supply 170 forsupplying gases to the chamber 150, a gas dispensing system 104 fordispensing gases, and a wafer platen 102 for supporting wafers 200 inthe chamber 150 during processing. The apparatus 100 is controlled by acontroller 160. Although the embodiments of the invention describedherein are discussed with respect to semiconductor wafer processing,other substrates may be processed in lieu of semiconductor wafers.

To supply wafers to the apparatus 100, a wafer transfer module 180communicates with the apparatus 100. The wafer transfer module 180comprises a loadlock and a wafer transfer robot. The details of thewafer transfer module 180 are not shown, since module 140 does not forma part of the present invention. The loadlock accepts wafers from afactory interface and temporarily stores the wafers prior to and afterprocessing. A wafer transfer robot moves the wafers from the load lockinto the stations 202A-202F for processing. To facilitate wafer accessto the chamber 150, the chamber wall contains a slit valve or other formof portal.

The chamber 150 defines a volume 151 within which a partial vacuum ismaintained during wafer processing. The vacuum is created in awell-known manner by at least one vacuum pump 153. The chamber 150 has asubstantially cylindrical shape and houses the gas dispensing system 104and the wafer platen 102.

The platen 102 is, in one embodiment, circular in shape having a pointof rotation disposed in the center of the platen 102. The platen 102 isfixed in the horizontal and vertical planes and rotates about itscentral axis in the horizontal plane.

The platen 102 is subdivided into wedge-shaped segments by purge gascurtain distributors 204A-204F. These segments are referred to herein asstations 202A-202F. Each of the curtain distributors 204A-204F produce avertical curtain of purge gas that isolates the gases used at any oneinstant within any one station from adjacent stations.

Each station 202A-202F comprises a wafer support 206A-206F. The wafersupports 206A-206F are arranged in an equidistantly spaced circularpattern about the hub 117. The wafer supports 206A-206F are affixed tothe hub 117 by a plurality of radial arms 208A-208F. The radial arms208A-208F contain wires that supply electrical signals to the supportpedestals 206A-206F. The wafer supports 206A-206F may be wafer pedestalsthat retain the wafer using mechanical clamp rings, vacuum chucks, orelectrostatic chucks. Additionally, each individual support may containa wafer thermal control (heating and/or cooling) element. As such, thewafer temperature may be independently adjusted at each process positionas the platen is rotated.

An actuator 155 causes the platen to move relative to the gas dispensingsystem 104. In one embodiment, the platen 102 may be caused to rotate bya direct drive motor, a concentric drive hub mechanism, a geared hub, abelt driven hub mechanism, or any technique commonly known in the artfor obtaining rotation of an object. The direction of rotation of theplaten 102 is indicated by the arrows 118. To facilitate rotation, theplaten 102 is mounted to a platen support 108 that is coupled to anactuator 155. In alternative embodiments, as discussed below, the gasdispensing system 104 may be caused to rotate or both the platen 102 andthe gas dispensing system 104 may be caused to simultaneously rotate.

A gas dispensing system 104 is disposed directly above the platen 102and is generally supported by the top of chamber 150. The system 104 issupplied various gases from the gas supply 170 via gas lines 116, 126and 128. The gas dispensing system 104 comprises a plurality of nozzleassemblies 120A-120F that are coupled to a gas distribution manifold130. The gas dispensing system 104 distributes gases to the nozzleassemblies 120A-120F from the various reactant gas lines 126 and 128 aswell as the purge gas lines 116.

As is discussed in detail with respect to FIGS. 3, 4 and 5 below, gasesare carried by the gas lines 126, 128 and 116 to the gas distributionmanifold 130. The gas distribution manifold 130 distributes gases to thenozzle assemblies 120A-120F. As discussed further below, the manifold130 could supply reactant gases sequentially to each of the nozzles orthe manifold 130 could simultaneously supply a plurality of gases toeach nozzle.

The apparatus 100 is controlled by controller 160. Controller 160comprises a central processing unit (CPU) 162, a memory 164 and supportcircuits 166. The CPU 162 is a microprocessor or microcontroller thatexecutes software stored in the memory 166 to produce control signalsfor the apparatus 100. The control signals include, but are not limitedto, gas pulse timing, gas pressure control, platen rotation control,wafer ingress and egress, wafer temperature, and the like. The CPU 162is coupled to various well-known support circuits 164 that includecache, power supplies, input/output circuits, clock circuits and thelike. The memory 166 may include at least one of random access memory,read only memory, removable storage, disk drives and the like. Thememory 166 stores software such as process routine 168 that is executedby the CPU to cause the ALD apparatus 100 to perform various processesand methods in accordance with the invention.

FIG. 3 depicts a bottom plan view of one embodiment of a gasdistribution manifold 130 and FIG. 4 depicts a cross-section of themanifold 130 taken along line 44 in FIG. 3. The manifold 130 comprises adistribution plate 300 defining a plurality of conduits 302 and 304 thatconnect the reactant gas lines 126 and 128 to the nozzle assemblies120A-120F. The conduits 302 and 304 extend radially from the inlet ports306 and 308 to the outlet ports 310 and 312. The conduits 302 and 304are fabricated at different levels within the plate 300 to maintainisolation of the gases that are carried to each station. A third inletport (not shown) may be used to supply a purge gas from the purge gasline 116 to one or more of the nozzle assemblies. Alternatively, thepurge gas may be coupled to either port 306 or 308, or both, using avalve within the gas supply 170. As such, purge gas could becontinuously supplied and reactant gas could be “switched” in using avalve to form a burst of reactant gas in the purge gas flow. In afurther alternative embodiment, each individual nozzle assembly could besupplied with a different gas, i.e., six inlet ports could be coupled tosix outlet ports to supply a different gas to each of the six nozzleassemblies 120A-120F. The manifold can be designed to couple any numberof reactant and purge gas conduits to any number of outlet ports.

FIG. 5 depicts a cross-sectional view of a nozzle assembly, e.g.,assembly 120A. The nozzle assembly 120A comprises a conduit 500 and ashowerhead 502. The conduit 500 defines a bore 504 that extends thelength of the conduit and sealably couples to outlet port (310 or 312 ofFIG. 3). The conduit is generally bolted to the manifold 300 using anO-ring 506 to form a gas tight seal between the conduit 500 and themanifold 300. Other techniques for attaching the nozzle assembly 120A tothe manifold 300 are readily available and known to those skilled in theart. The showerhead 502 comprises a plenum 508 for distributing gas fromthe bore 504 to a plurality of apertures 510. The pattern of theapertures 510 is designed to uniformly supply gas across a wafer (asdiscussed below). In some embodiments of the invention, a showerhead maynot be used and the bore 504 may be terminated with a spray nozzle.

FIG. 9 depicts a vertical, cross-sectional view of another embodiment ofa nozzle 900 and FIG. 10 depicts a plan view of the nozzle 900. Thenozzle 900 comprises a plurality of zones 902, 904, 906 through whichdifferent gases may be dispensed. In some instances, such as in a CVDmode that will be discussed with reference to FIG. 12 below, all thezones may supply the same gas to a processing station.

Each zone 902, 904, and 906 comprises a plurality of conduits 908, 910,and 912 that are each coupled to respective plenums (shown in phantom as924, 926, and 928) that distribute gas to at least one respective port914, 916, 918 located in the faceplate 922. Gases that are supplied by amanifold (similar to the manifold in FIGS. 3 and 4 that has been adaptedto distribute a plurality of gases to the nozzles) to each conduit 908,910 and 912 flows to the port(s) 914, 916 and 918 in each respectivezone 902, 904, and 906 without mixing. Although the embodiment shown hasa plurality of ports linearly arranged in each zone, other arrangementssuch a single port having a circular or rectangular shape (i.e., aslot), a two dimensional array of ports, combinations of port shapes andthe like may be used and are considered to be within the scope of theinvention. Furthermore, the embodiment shown depicts three zones,however, more or less zones are contemplated as being within the scopeof the invention. Also, each zone may have a different shape or size ofthe port arrangement to tailor the ports to the type of gas and adesired gas disbursement pattern.

In operation, the wafer 200, positioned on the rotating platen, moves ina direction represented by arrow 920 beneath the nozzle 900. In thismanner, as few as a single multi-zone nozzle can be used to deposit afilm upon a plurality of wafers. However, to increase wafer throughput aplurality of nozzles is generally used.

As a wafer moves beneath the nozzle 900, the gas G₁ from port 914 isadsorbed by the wafer 200 as the wafer passes beneath the port 914. Theamount of gas applied to the wafer is defined by the speed of rotationof the platen. As the wafer moves beneath port 916, a second gas G₂ isapplied to the wafer. Then, as the wafer 200 moves beneath port 918, athird gas G₃ is applied to the wafer. In one embodiment of theinvention, gases G₁ and G₃ are reactive gases and gas G₂ is a purge gas.If, for example, gas G₁ were silane, gas G₃ were tungsten hexafluorideand gas G₂ was Argon, then gas G₁ would be adsorbed first, gas G₂ wouldremove any excess silane from the wafer surface, and lastly gas G₃ wouldprovide tungsten to react with the silane to form a thin tungsten filmon the wafer. A detailed process description is described with respectto FIG. 13 below.

FIG. 11 depicts a plan view of another embodiment of a faceplate 1108 ofa nozzle 1116. In this embodiment, each gas exits the faceplate 1108through zones 1102, 1104, and 1106 defined by gas disbursement channels1110, 1112, and 1114. The channels 1110, 1112, and 1114 are arcuate,where the arc of each channel is similar to the arc of the edge of asubstrate (wafer) that is being processed. The peak of each arc (alongline 1118) is aligned with the path of the wafer beneath the nozzle 1116on the rotating platen. Such arcuate channels 1110, 1112 and 1114 areintended to supply gas uniformly to the substrate such that all pointson the substrate in an arcuate swath are exposed to the gassimultaneously. As with the previous embodiment, the disbursementchannels are merely examples of a type of distribution ports. Thoseskilled in the art will understand that the channels could be replacedwith holes, arrays of holes, holes of various shapes, or combination ofholes and channels. The size and shape of each zone may be tailored tothe dispersion rate, adsorption dynamics, process parameters, device orsubstrate topography and gas residence times desired for each particulargas.

FIG. 12 depicts a dual plumbed, gas distribution system 1200 to be usedwith the multi-zone gas nozzles 900/1116. The system 1200 comprisesthree gas supplies 1202, 1204, and 1206, a plurality of mass flowcontrollers (MFC) 1208, 1210, 1212 and 1214, a plurality of two positionvalves 1216, 1218, 1220, a plurality of gas splitters 1222, 1224, and1226 and a premix chamber 1228. The intent of the system is to permitgases from each supply 1202, 1204 and 1206 to be provided to the lines1230, 1232, and 1234 that carry gas to the nozzles 900/1116 as well asallowing premixed combinations of gases to be provided to one or more ofthe lines 1230, 1232, 1234. For example, a single gas can be supplied toeach line in an ALD mode or a premixed combination of gases may besimultaneously supplied to all the lines in a CVD mode.

In an ALD mode, gas from supply 1202 is coupled through a gas splitter(a T-coupler) 1222 to the MFC 1208. The MFC 1228 meters the amount ofgas that is supplied to the two-position valve 1216. In a firstposition, the valve 1216 directs the gas from the MFC 1208 to the line1230. Similarly, in an ALD mode, gas supply 1206 provides gas throughthe MFC 1214 to the two-position valve 1220 and to line 1234. Also inthe ALD mode, gas supply 1204 is coupled through a two-position valve1218 to line 1232. In this manner, metered amounts of gas are suppliedseparately to each zone of the nozzles. The dosing of the wafer can besynchronized with the rotation of the platen. As is described furtherwith reference to FIG. 6 below, each station 202A-202F of FIG. 2deposits a pair of gases as needed to complete a single deposition of alayer. The thickness of the layer may be controlled by the speed ofrotation of the platen. The repeated rotation of the platen causesadditional layers to be accumulated with each pass of the wafer under amulti-zone nozzle. Consequently, the process can be used for highconformity deposition of seed layers and bulk fill of materials.

In a CVD mode, gas from supplies 1202 and 1206 is coupled throughsplitters 1222 and 1224 to MFCs 1210 and 1212 and into the premixchamber 1228. In the premix chamber, the gases are caused to mix.Generally, these gases are reactants that will react when they areexposed to a heated substrate, i.e., a silane and tungsten hexafluoridereaction to produce tungsten. The mixed gases are coupled from thepremix chamber 1228 through a three-way splitter to a second input portof valves 1216, 1218 and 1220. Through manipulation of the valves 1216,1218, and 1220 into a second valve position, the premixed gases may beapplied to one or more (including all) the zones of the multi-zonenozzles 900/1116.

As such, the multi-zone nozzle may be used for both ALD and CVDdeposition as disclosed in detail with respect to FIG. 13 below. Inshort, the apparatus of FIG. 1 may deposit an ALD film using themulti-zone nozzle to form a highly conformal seed layer and then switchto the CVD mode to complete a bulk fill process without stopping therotation of the platen. As such, considerable throughput performanceimprovement is achieved. In addition, different reactants could be usedduring seed and bulk deposition. For example, in an illustrative WF₆chemistry, the ALD mode may use WF₆ and B₂H₆ to form a first tungstenlayer and then switch to WF₆ and SiH₄ to form a second tungsten layerover the first layer. The second layer will bulk fill a feature withtungsten. The first layer may be a nucleation layer or seed layer. Sucha technique would require additional gas supplies and plumbing to adaptthe gas distribution system of FIG. 12 to supply the various gases tothe nozzles. This WF₆ chemistry is illustrative of one possiblechemistry, it is to be appreciated that other chemistries may be used.

FIG. 6 depicts a schematic diagram of a single station 140A of theapparatus 100 of FIG. 1. The station 140A comprises a nozzle assembly120A, a wafer support 206A, and a pair of purge curtain distributors204A, 204F. The nozzle assembly 120A is coupled to a reactant gas supply600 (and, possibly, also a purge gas supply 602) and the purge curtaindistributors 204A, 204F are coupled to a purge gas supply 602. If thenozzle is a multi-zone nozzle, then it is coupled to a plurality of gassupplies such as shown in FIG. 12.

The wafer support 206A may comprise an electrode 604 and an embeddedtemperature control element 606. The electrode 206A is coupled to avoltage supply 608 that applies a voltage to the electrode and the wafer(to facilitate chucking of the wafer 200 by electrostatic force).Alternatively, a clamp ring or vacuum could be used to retain the wafer200 on the support 206A.

The temperature control element 606 may be a resistive heater elementthat is coupled to a heater power supply 610. The temperature element606 could also be a fluid jacket or some other temperature controlelement. The temperature control element 606 is energized to maintainthe wafer 200 at a predefined temperature. Alternatively, or in additionto the embedded element 606, one or more heater lamps 616 and a lampheater power supply 618 may be used to heat the wafer 200. If a processrequired wafer cooling, then the temperature control element 606 wouldbe a cooling plate or element. The wafer support could contain both aheating and cooling element that can be used to selectively heat or coola wafer. Furthermore, external energy sources such as a laser, amicrowave power source, or a RF power source may be used in pulse orsteady state mode to activate the precursor used in the reaction, i.e.,additional energy sources can be used to activate oxygen in theformation of Al₂O₃ using an ALD technique.

In operation, using a single zone nozzle, the wafer is positioned on thesupport 206A and retained. A reactant gas (e.g., silane) is supplied tothe nozzle assembly 120A. The gas is typically supplied as a short pulseor burst of gas 612 that exits the showerhead 502 proximate the wafer200. Alternatively, a continuous flow of purge gas may be supplied fromgas supply 600 and intermittent bursts of reactant gas may be injectedinto the continuous flow of purge gas using a valve 620. The temperatureof the wafer 200 is maintained by the temperature control element 606 tofacilitate adsorption of the silane on the surface of the wafer 200.Purge gas is continuously supplied to the purge curtain distributors204A and 204B such that a curtain 614A and 614F of purge gas is formedon either side of the wafer support 206A. The curtains 614A and 614Fensure that the reactant gas 612 is constrained to a volume near thewafer support 206A.

FIG. 7 depicts a flow diagram of a method 700 of operation for theapparatus 100 as controlled by controller. The method 700 represents theoperation of the apparatus 100 for depositing a tungsten layer upon asemiconductor wafer using a reaction between SiH₄ and WF₆. In thisexample, the tungsten deposition is repeated three times (i.e., one passthrough a six station ALD apparatus 100) to form a relatively thintungsten layer. To increase the thickness, a wafer may be repeatedlyprocessed by the six stations.

The method 700 begins at step 702 and proceeds to step 704 wherein thepurge gas curtains are formed between the stations. These curtains aremaintained throughout the remaining steps of the method. At step 706,wafers are loaded onto each wafer support to fill all the waferprocessing positions. Each position is defined by a nozzle assembly,i.e., position 1 is beneath nozzle assembly 120A, position 2 is beneathnozzle assembly 120B, and so on. In step 706, as each wafer is loaded, aretention force is applied to retain the wafer on the support. At step708, the wafer temperature is set at each position, then at step 710, apulse of SiH₄ is applied to the wafer in positions 1, 3 and 5. After thegas is applied at positions 1, 3 5, the platen is turned, at step 712,to the next position. At step 714, a pulse of WF₆ is applied to thewafers in positions 2, 4 and 6. At step 716, the method queries whetherthe processing is to continue. If the query is affirmatively answered,steps 708-714 are repeated to deposit another tungsten layer, e.g., amono-layer. If the query is negatively answered, the wafers are unloadedat step 718 and the method stops at step 720. The foregoing process isdescribed having the steps of the process performed in sequential order,however, one or more of the steps may be performed simultaneously andsuch a process is considered to be within the scope of the invention.

Alternatively, wafers may be loaded one at a time into the apparatus. Aseach wafer is loaded, the temperature can be set and the silane adsorbedupon the wafer. After the platen is rotated, the WF₆ may be applied tothe wafer, and a new wafer positioned at position 1 for silaneadsorption. As each new wafer is added to the apparatus, a process canbe accomplished at each position. Once all the positions are filled withwafers, the processing may be applied at each position as the platen isrotated.

After a pass through the method 700, both reactant gases (e.g., SiH₄ andWF₆) have been dispensed over the wafer substrates 306 in short bursts.After each burst of reactant gas, a purge gas such as argon may beapplied through each nozzle assembly or the purge gas may becontinuously applied. As such, steps 710 and 714 may each be followed bya flow of purge gas. Reactant gases are prevented from mixing outsidetheir respective stations by the purge gas curtains. The aforementionedmethod steps 708 through 714 may be repeated between 10 and 50 cycles inorder to achieve a desired deposition of thickness of tungsten on thewafer.

Other processing methods may be employed by this embodiment of theinvention. One such method is to continuously flow reactant gases(and/or purge gases) from the nozzle assemblies while separating thestations with the inert gas purge curtains. The platen would becontinuously rotated such that a different reactant gas would be appliedto a wafer at each position for a time period defined by the rotationspeed of the platen. Employing this processing method, less than 30cycles may be required before the desired deposition thickness is formedon the wafers. To enhance wafer throughput, the platen rotation speedmay be modulated in a sinusoidal pattern such that rotation is slowed asa reactive gas is being applied and rotation speed is increased when thewafers are passing through a purge gas curtain.

In a further embodiment of the invention, the stations may be adapted toperform a complete metallization step as well as other integratedcircuit fabrication process. For example, positions 1 and 2 could beused to deposit a first tungsten layer by having a wafer repeatedlyvisit position 1 for a SiH₄ application and position 2 for a WF₆application. Once a first layer is complete, the wafer can be moved toposition 3 where a hydrogen reduced tungsten bulk deposition processcould be performed to deposit a second layer upon the first layer.Stations 4, 5 and 6 could be used for processing a second set of wafersin a similar manner.

In another embodiment of the invention using single zone nozzles, eachstation is supplied with both reactant gasses and a purge gas. Eachreactant gas is simultaneously applied to a wafer synchronously, whilethe wafer is stationary. The gases are applied using an ALD technique ofshort bursts of gas followed by purge gas application. For suchsynchronous operation with the same gas being applied at all stationssimultaneously, the purge gas curtains may be unnecessary. To complete ametallization process, bulk deposition at all the stations may followthe ALD deposition process.

Furthermore, the process may be adapted to load all the wafers into theapparatus, set the process temperature and then soak all the wafers in afirst soaking gas. Such an initial process may deposit a silicide layer(e.g., titanium silicide), upon the wafer. The silicide layer depositionis followed by a purge step where a purge gas is applied to the wafersthrough all the nozzles. Thereafter, a first reactant gas is suppliedthrough all the nozzles as the platen rotates, followed by anapplication of a second reactant gas. Another reactant gas or a purgegas may be applied prior to the process ending. In this manner, theapparatus is capable of deposing a first and second layer, where, forexample, a silicide layer can be deposited prior to depositing anucleation layer.

FIG. 13 depicts a flow diagram of a process 1300 for depositing a layerusing a multi-zone nozzle. As one embodiment of the process, the processis described as used to deposit a first tungsten layer using an ALDmode, followed by an optional tungsten bulk fill process using a CVDmode. Those skilled in the art will realize that the process 1300 may beadapted to use various other gases to deposit other films.

The process 1300 begins at step 1302 and proceeds to step 1304 whereinthe purge curtains are formed. At step 1306, the wafers are loaded ontothe wafer supports. At step 1308, the apparatus 100 establishes anappropriate wafer temperature for each wafer. At step 1310, the platenis rotated and the various gases are applied to the multi-zone nozzles.In one embodiment, the first zone encountered by the wafer as it rotatesinto each station delivers silane, the second zone delivers a purge gasand the third zone delivers tungsten hexafluoride. As the wafer passesbeneath the nozzles that disperse these gases, the process operating inthe ALD mode forms a first tungsten layer. The rotation speed of theplaten can be adjusted to increase or decrease the thickness of thedeposited layer. At step 1312, the process 1300 queries whether the ALDmode processing is complete. If the query is negatively answered theprocess continues to rotate the platen and apply the gases to continueto form the first layer. The more stations that a wafer passes through,the thicker the first layer becomes.

When the query of step 1312 is affirmatively answered, the processproceeds to the query in step 1320. The query in step 1320 requestswhether an optional bulk deposition process is to be initiated using aCVD mode. If the query of step 1314 is negatively answered, the processcontinues to step 1320 where the wafers are removed from the apparatusand the process is stopped at step 1322. However, if the query isaffirmatively answered, the process 1300 proceeds to step 1316. At step1316, the platen is rotated while gases are applied that will bulk fillthe features on the wafer i.e., a second layer is deposited upon thefirst layer. The bulk fill process may be a CVD process wherein one ormore zones has a mixture of gases applied to the multi-zone nozzle. Themixed gases, for example, WF₆ and SiH₄, do not react in the gas phasesuch that they can be mixed and supplied to the wafer simultaneously.The gases react with one another upon the heated wafer surface to form atungsten layer. At step 1218, the process queries whether the CVDprocess is complete. If the query is negatively answered, the processcontinues the CVD deposition. Otherwise, the process removes the wafersat step 1320 and stops at step 1322.

Although the foregoing description of the method describes the processsteps as performed in a sequential order, some of the steps may beperformed simultaneously or in a different order to deposit one or morelayers of material in accordance with the invention. Furthermore, theapparatus 100 can also be used to deposit layers of material separatelyusing either the CVD mode or the ALD mode.

Referring to FIG. 8, another embodiment of the present invention isshown, wherein the gas distribution system 804 radiates outward from acentral hub 830 that is mounted to a rotating platen assembly 802. Inthis embodiment, as in the previous, a wafer transfer module 180,including a wafer transfer robot (not shown), is coupled to theapparatus 800. The apparatus 800 is comprised of a rotating platenassembly 802 and a gas distribution system 804.

The platen assembly 802 comprises a plurality of wafer supports810A-810E and rotates, for example, in the direction of the arrow 814.The platen 802 and wafer supports 810A-810E are similar to platen 102and supports 206A-206F of FIG. 2. As such, the platen and its supportsshall not be described further. During processing, the platen may rotateto position the wafers beneath the gas sources or, alternatively, theplaten may be stationary and the gas sources may be moved into positionabove the wafers.

The gas distribution system 804 comprise a plurality of arms or wands812, 822, 824 and 826, hereinafter referred to as gas dispensing arms,that transmit gas from the central hub 816 to a region above the wafers.Although four arms are depicted, more or less arms may be used dependingupon the processes that are to be performed. The gas dispensing arms812, 822, 824 and 826 may, for example, rotate above the platen in adirection that is opposite to the direction of rotation of the platenassembly 802. The gas dispensing arms 812, 822, 824 and 826 may alsorotate in an indexed manner, i.e., rotate using an intermittentrotational movement wherein the arms rotate into alignment with aparticular wafer, stop, dispense gas, and then move to another waferlocation.

The gas dispensing arms 812, 822, 824 and 826 project from a series ofstacked gas manifolds 840 that form a portion of the central hub 816.The manifolds 840 may rotate at different rates of speed independent ofeach other. Each segment of the manifold is stacked upon the othersegments with one or more of the gas dispensing arms 812, 822, 824 and826 projecting from the sides or top of the hub 816. A series of nozzles820 are located along the bottom of each of the gas dispensing arms 812,822, 824 and 826 near the end thereof to allow gas to exit from therespective gas dispensing arms. The nozzles 820 are designed to projectthe gas downward at the substrate support 810A-810F. The gas dispensingarms 812, 822, 824 and 826 are coupled to a gas supply 828 via gassupply lines 832, 834 and 836. Each gas-dispensing arm 812, 822, 824 and826 may contain a different reactant gas or inert gas for use in theatomic layer deposition process.

In practice, wafers 806 are transferred from the wafer transfer module180 by the wafer transfer robot (not shown) onto the wafer supports810A-810E. The wafer supports 810A-810E secure the wafers 806 so as toprevent movement. Once secured, the wafer supports 810A-810E are indexeduntil all the stations are loaded. A gas-dispensing arm 812, 822, 824 or826 is queued to pass over at least one of the wafer supports 810A-810E.As the gas-dispensing arm 812, 822, 824 or 826 passes over at least oneof the wafer supports 810A-810E, the arm 812, 822, 824 or 826 dispensesa first reactant gas (e.g., silane) over the wafer 806, beginning theALD process. The wafers 806 will adsorb some of the reactant gas and therest will be purged away by an inert gas supplied by another gasdispensing arm passing over the wafer support. Subsequently, a secondreactant gas dispensing arm 812, 822, 824 or 826 moves over the top ofthe wafer supports 810A-810E and dispenses a second reactant gas (e.g.,WF₆).

The second reactant gas reacts with the adsorbed gas on the wafer 806 toform a thin film on the wafers 806. Another one of the gas dispensingarms 812, 822, 824 or 826 that dispenses an inert purge gas is alsocaused to rotate over the wafer supports 810A-810E dispensing inertgases so as to prevent the accumulation of the reactant gas proximatethe wafers. The inert gas may also be dispensed in intervals so as toprevent stray reactant gases from contaminating other wafers 806 on thesubstrate supports 810A-810E. Purge gas could be supplied continuouslyfrom all the arms and intermittent bursts of reactant gas may be coupledto the appropriate arm at an appropriate time.

The rotational motion of the platen assembly 802 during processing maybe continuous, intermittent (indexed) or stationary. The motion of thegas distribution arms 812, 822, 824 and 826 may be continuous,intermittent or the arms may be stationary. Generally speaking, eitherthe arms or the platen rotate relative to one another to facilitate gasapplication to the wafers. If the arms are rotatable, eachgas-dispensing arm 812, 822, 824 and 826 in one embodiment of theinvention rotates independent of the others as well as being independentof the platen rotation. In another embodiment, the arms may rotate inunison. Each of the gas dispensing arm's movements may be adjusted so asto achieve optimum performance during the atomic layer depositionprocess. For example, the movement may be modulated in a sinusoidalmanner to slowly rotate the arms as gas is being dispensed and rapidlyrotate the arms as the arms are being moved into position over the nextwafer.

As described above, the apparatus and method according to the presentinvention is more efficient and effective compared to the conventional,single chamber apparatus and methods. Therefore, layers of materialformed on wafers by the present invention are more uniform and morequickly produced than by other methods.

Although various embodiments that incorporate the teachings of thepresent invention have been shown and described herein. Those skilled inthe art can readily devise many other varied embodiments that stillincorporate these teachings.

1. A method of depositing a material on a wafer in a deposition chamberhaving a plurality of deposition stations comprising: (a) forming a gascurtain between deposition stations; (b) positioning a wafer on one of aplurality of wafer supports in a first deposition position; (c)introducing a first deposition gas proximate said first wafer; (d)rotating the wafer into a second deposition position; and (e)introducing a second deposition gas proximate said first wafer.
 2. Themethod of claim 1 further comprising the step of applying a purge gas tothe first wafer after the introduction of the first deposition gas andthe second deposition gas.
 3. The method of claim 1 further comprisingthe step of establishing a predefined temperature for the wafer at eachof the first and second deposition positions.
 4. The method of claim 1further comprising forming purge gas curtains on either side of eachwafer support.
 5. The method of claim 1 further comprising: (f) rotatingthe wafer to the first deposition position and repeating steps (c), (d)and (e).
 6. The method of claim 1 further comprising: positioning asecond wafer on a wafer support in the first deposition position afterthe first wafer is rotated to the second deposition position.
 7. Themethod of claim 1, wherein, at each deposition position, supplying acontinuous flow of purge gas having a reactant gas intermittentlyinserted into the continuous flow of purge gas as a burst of reactantgas.
 8. The method of claim 1, wherein the reactant gas used at thefirst deposition position is silane and the reactant gas used at thesecond deposition position is tungsten hexafluoride.
 9. A method ofprocessing a substrate comprising: supplying a plurality of gases to amulti-zone nozzle, where a different gas is supplied to each zone in aplurality of zones; and disbursing gas upon a substrate from each of thezones as the substrate moves beneath the multi-zone nozzle, where eachof the gases contacts the substrate in a sequential order.
 10. Themethod of claim 9, wherein the plurality of zones comprises three zones.11. The method of claim 9 further comprising supplying a gas mixture tothe multi-zone nozzle and dispensing the gas mixture from one or more ofthe zones.
 12. The method of claim 1, wherein the step of disbursing gasin a sequential manner forms a layer through an atomic layer depositionand disbursing a gas mixture forms a layer through a chemical vapordeposition.